The subject matter of the present invention relates to a workstation based apparatus and associated method for automatically identifying fault curves in seismic data by using a horizon time structure, reflective of one of the horizons inherent in the seismic data, to automatically identify valid gaps in the horizon time structure having a proper length and slope, to locate midpoints in the valid gaps, to draw fault cuts at the midpoints of the gap at a user defined inclination, and to extend the horizon to the newly drawn fault cuts thereby automatically identifying the fault curves in the seismic data.
Faulting of stratigraphic subterranean formations creates hydrocarbon traps and flow channels. As a result, accurate identification of the fault curves and fault surfaces is essential to the interpretation of most seismic data volumes. Those persons involved in exploration to locate such hydrocarbon traps and flow channels in the formations use an interactive workstation on which is displayed sections of seismic data. The seismic data includes a plurality of fault curves or fault cuts, each fault cut representing the intersection of a fault surface with a horizontal "horizon" inherent in the seismic data. However, when using most existing workstation tools that include interactive computer programs, the interpretation of fault cuts on horizons in the seismic data is tedious and time consuming; that is, the workstation operator must view the seismic data volume on the workstation display, manually determine by viewing the seismic data where a plurality of horizons are located in the seismic data, and manually determine by viewing the plurality of horizons where a plurality of fault cuts are located in each of the plurality of horizons in the seismic data volume. This manual method for determining the fault cuts in the horizons on the seismic data, aside from being very tedious and time consuming, produced an inconsistent set of results in terms of accuracy because the accuracy of the results depended upon the mental awareness of the workstation operator.
Therefore, a more accurate method and apparatus adapted to be disposed in a computer workstation for identifying fault cuts in seismic data is needed for automatically determining, from an input seismic data volume that contains a plurality of horizons, where one or more fault cuts are located in each of the plurality of horizons in the seismic data.
For example, one such method and apparatus, for automatically determining where a plurality of faults are located in the plurality of horizons in seismic data, is disclosed in U.S. Pat. No. 5,537,320 to Simpson et al, the disclosure of which is incorporated by reference in this specification. In the Simpson et al patent, a seed fault is placed by a user in the seismic data, and a plurality of fault curves are determined, by a computer program executing in a workstation, in response to the seed fault placed by the user in the seismic data.
However, recalling that the seismic data includes a plurality of horizons and each of the plurality of horizons in the seismic data include a plurality of faults, while the Simpson et al patent does require the seismic data and a seed fault in the seismic data for determining the plurality of faults in the seismic data, the Simpson et al patent does not determine one or more fault cuts in a horizon (also called "a horizon time structure") from the horizon time structure itself.